This invention relates to new and useful improvements to augers, in particular an auger used for conveying grain and other particulate material. More specifically the invention relates to a material conveying auger having an improved intake designed for increased safety of persons working in the near vicinity thereof.
Conventional grain augers comprise a tubular or cylindrical rigid outer casing or housing in which is housed a rotary feed screw having a constant diameter rigid metal helical flight which extends from an intake at one end of the casing to a discharge end at the opposite end of the casing. In many instances, the intake end of the auger, ie where the grain is fed into the auger, a portion of the auger flighting is exposed and projects outwardly from the outer casing, with the outer end of the main auger shaft being journalled in an end bearing assembly which itself is supported by a plurality of circumferentially spaced longitudinal support rods which are fixed to the casing and project beyond the open intake end of the casing. The projecting support rods provide partial shielding around the intake end of the auger for preventing a limb, eg a hand or leg, being accidentally caught in the auger intake end flighting. However, it is not uncommon for an operator of a grain auger to lose a finger, or even part of an arm, as a result of insufficient safety guards at the auger intake end during operation of the auger. It will be appreciated that the intake flighting where it enters the open end of the rigid metal outer casing and the end edge of the rigid casing effectively function as a slicer and will readily slice an obstruction, eg a finger, which becomes trapped therebetween, especially when the edges of the metal casing and metal flighting become sharpened through wear from use.
It is also known for manufacturers of grain augers to fit protective guards or shields over the auger intake end in order to minimise the likelihood of injury to the operator; however, it has been found that the use of such guards around the intake end of the auger interferes with the pick-up and conveyance of the material which reduces the working capacity of the auger. As a result, operators quite often remove the shields or guards, and of course, once removed, there is the potential for a serious injury.
A further problem with existing farm augers is that there is no safeguard for stopping the rotation of the flighting in the event of an obstruction engaging within the intake end or the intake end becoming choked with material, eg fertiliser. In cases where the obstruction is a foreign object such as a fertiliser bag, the object can be conveyed into the section of the auger casing where it can be difficult to remove should jamming of the auger occur. It would be advantageous if the auger was designed so that its intake end flighting stopped rotating in an overload situation, while still permitting the downstream portion of the auger to continue rotating so as to help clear the overload before the intake flighting resumed its rotation. In the situation where the obstruction is a person""s limb, eg leg or arm, it is vital that drive to the intake end flighting cease virtually instantaneously.
It is an object of the present invention to provide an improved auger assembly which is designed so that the likelihood of any serious injury being suffered by an operator (or any other person in the vicinity of the auger intake end) in the event of his or her leg or arm (or a part thereof) accidentally being caught in the auger intake end, is drastically reduced.
It is another object of the present invention to provide an improved auger assembly which incorporates a safety overload prevention device which will operate to disengage drive to the intake flighting should an overload occur, eg as a result of an obstruction, such as a leg or arm, becoming trapped in the auger intake.
It is a still further object of the present invention to provide a safety clutch mechanism for the intake end of an auger assembly which is easy to assemble and maintain and which an be easily disengaged for servicing purposes.
It is a still further object of the present invention to provide a replacement auger intake section which can be readily fitted to an existing auger for improving its operating safety by minimising the risk of injury being suffered by an operator should one of his limbs, or a part thereof, become caught in the auger intake end, and one which allows an operator to readily change the intake flighting where a different pitch is required.
It is yet a still further object of the present invention to provide an improved auger intake unit which is simple in construction, economical to manufacture and .which does not materially affect the capacity of the auger to convey material therealong.
According to one aspect of this invention therefore, there is provided an improved material conveying auger assembly of the type which includes an elongate tubular casing having an intake end and a discharge end, a drive shaft extending coaxially through the casing and journalled for rotation therein, and helical flighting on said drive shaft, the improvements comprising (i) a replacement auger intake section adapted for connection to the drive shaft so as to rotate therewith, said intake section having helical flighting formed of resilient flexible wear resistant material and (ii) a soft, pliable tubular extension sleeve attachable to the intake end of said casing so as to project axially outwards therefrom, said extension sleeve being arranged to encircle at least a portion of said intake section and its flighting.
Preferably the intake end flighting is formed of polymeric material, eg polyurethane, having a Shore xe2x80x9cAxe2x80x9d hardness value in the range 60-100, most desirably a value of around 90.
Desirably the extension sleeve is formed of a rubber or rubber-like material having a Shore xe2x80x9cAxe2x80x9d hardness value in the range 35-60, most desirably a value of 45. Generally, the extension sleeve will be formed of a durable material which is quite softer and more pliable than the material of the intake flighting but at the same time possess sufficient radial stiffness to support itself under operating conditions.
Preferably the extension sleeve is slidably fitted over the open intake end of the casing and is clamped thereto by releasable clamping means.
The resiliently deflectable intake end flighting and the soft rubber extension sleeve at the intake end of the auger casing eliminate the sharp metal edges normally present in a conventional auger and thereby greatly minimise the likelihood of a serious injury being suffered should a person""s limb or limbs become caught in the intake end of the auger. With the arrangement of the present invention, it has been shown that even with the auger rotating at speeds in the order of 400-500 rpm, a person""s fingers can be trapped in the intake end flighting and subsequently withdrawn therefrom without serious injury or damage. The soft rubber sleeve portion of the auger casing at the intake end thereof, being easily deformable, will allow the fingers, caught by the intake flighting to be pulled out without serious consequences.
Preferably the extension sleeve has associated therewith a feed tray portion which projects axially away from the outer end of the sleeve and extends along the underside of the intake section. The tray may be a separately formed member and have its own attachment means for attaching it to the auger casing, or the tray can be integrally formed with the extension sleeve.
According to another aspect of the invention, there is provided a safety clutch mechanism arranged to drivingly connect the auger intake flighting section to the main auger shaft so that the intake flighting, under normal operating conditions, will rotate simultaneously with the main auger shaft or, in the event of an obstruction becoming caught in the intake end of the auger, drive to the intake flighting will be disengaged and the intake flighting will be stationary relative to the main auger shaft.
Preferably the clutch mechanism is of the dog clutch type and comprises a clutch driver element which is adjustable to allow axial alignment of the flightings and then locked in position by a securing bolt so that it is fast with the main drive shaft, and a driven clutch plate element axially movable with respect to the driver element for engaging and disengaging the drive.
Preferably, the clutch mechanism is constructed and arranged so that when an overload occurs, the driven clutch plate element will disengage from its driver element and drive to the auger intake flighting will cease and will not re-engage until the overload is cleared.
Preferably, drive is transmitted to the intake flighting shaft portion via a bodily rotatable coil spring mounted on the drive shaft between the driven clutch plate element and a drive coupling member on the intake flighting shaft portion.
The clutch assembly is arranged so that it will only disengage with a shock overload, and will not disengage under normal constant loading conditions.
Preferably the drive coupling member on the shaft portion of the intake flighting comprises a quick release cammed bush selectively rotatable and axially movable between a normally locked clutch engaging position and an unlocked position which disengages the clutch mechanism and thereby enables the intake flighting to be freely rotated about the drive shaft. This is desirable for maintenance reasons where an operator may wish to check that the intake flighting is freely rotating on the drive shaft. It is not unusual for some clogging to occur between the intake flighting shaft portion and the drive shaft on which it rotatesxe2x80x94particularly where the auger is being used for conveying fertiliser materials and moisture penetrates into this region.
Desirably, the clutch mechanism is designed so that it will only engage when the intake flighting is properly aligned with the flighting on the main drive shaft, and in the event of the clutch temporarily slipping due to an overload, it will only reengage with the flightings properly re-aligned.
In order to more fully explain the present invention, two preferred embodiments thereof are described hereunder in some further detail with reference to and as illustrated in the accompanying drawings wherein:
FIG. 1 is a fragmentary perspective view of an auger intake assembly fitted to the intake end of a conventional auger (which has had a portion of its shaft and flighting at the intake end thereof cut-off), according to a first embodiment;
FIG. 2 is an exploded perspective view of the assembly shown in FIG. 1;
FIG. 3 (a) is a fragmentary elevational view of the outer end of the auger intake section showing only the clutch mechanism in its normally engaged position;
FIG. 3 (b) is a view similar to FIG. 3 (a) showing the clutch in a disengaged state (by virtue of a shock overload);
FIG. 3 (c) is a view similar to FIG. 3 (a) showing the manner in which the clutch is disengaged by operation of the drive coupling member on the intake flighting shaft;
FIG. 4 is a transverse sectional view taken through the section of the intake flighting shown in FIG. 1; while
FIG. 5 is a fragmentary view of the auger intake end showing the intake flighting and an extension sleeve fitted to the end of the main auger casing, according to a second embodiment of the invention.